1. Field of the Invention
The present invention relates to a photoelectrode substrate for a dye sensitizing solar cell, and a method for producing the same. More specifically, the invention relates to a photoelectrode substrate for a dye sensitizing solar cell wherein an electrolyte is filled in a space between a counter electrode of a counter electrode substrate and the photoelectrode substrate, and a method for producing the same.
2. Description of the Prior Art
In recent years, from the point of view of environmental issues, solar cells for converting light energy to electric energy have been widely noticed. In particular, dye sensitizing solar cells have been widely noticed since the costs for producing them can be low. Conventional dye sensitizing solar cells are not intended for practical use since they have a low photoelectric transfer efficiency. Recently, there has been developed a technique for using a porous semiconductor electrode having a large surface area to cause the electrode to adsorb a large amount of dye to conspicuously enhance the photoelectric transfer efficiency of a dye sensitizing solar cell (see, e.g., Japanese Patent Unexamined Publication No. 5-504023 (National Publication of Translated Version of PCT/EP91/00734)).
As a conventional dye sensitizing solar cell using such a technique, there is known a dye sensitizing solar cell 101 which comprises a photoelectrode substrate 102, a counter electrode substrate 103, and an electrolytic solution 104 filled in a space therebetween, as schematically shown in FIG. 4. The photoelectrode substrate 102 of the dye sensitizing solar cell 101 comprises a substrate member 105, a transparent electrode film 106 formed on the surface 105a of the substrate member 105, and a porous semiconductor electrode film 108 of titanium oxide or the like formed on the transparent electrode film 106, the porous semiconductor electrode film 108 adsorbing a dye thereon. The porous semiconductor electrode film 108 is formed by a method comprising the steps of applying a suspension containing semiconductor particles on the transparent electrode film 106, and drying and burning it. The counter electrode substrate 103 of the dye sensitizing solar cell 101 comprises a counter substrate member 110, and a counter electrode 111 formed on the counter substrate member 110 by coating a catalyst such as platinum thereon. The substrate member 105 and the counter substrate member 110 are arranged so that the counter electrode 111 faces the porous semiconductor electrode film 108 at an interval. The electrolytic solution 104 is filled in the space between the counter electrode 111 and the porous semiconductor electrode film 108 to form the dye sensitizing solar cell 101. In the dye sensitizing solar cell 101, dye molecules adsorbed on the surface of the porous semiconductor electrode film 108 are designed to absorb light to inject electrons into a semiconductor to use the semiconductor electrode film 108 as a negative electrode to generate power.
However, in the above described conventional dye sensitizing solar cell 101, the movement of electrons from the porous semiconductor electrode film 108 to the transparent electrode film 106 occurs due to diffusion, so that the reverse movement of electrons from the transparent electrode film 106 to the semiconductor layer also occurs simultaneously. Therefore, the residence time of electrons in the porous semiconductor electrode film 108 is increased, so that there is a problem in that the probability of recombination of the electrons with the dye is increased to deteriorate the power generation characteristics of the dye sensitizing solar cell 101.